I am in the process of adding PDF versions of my books to DriveThruRPG.
the Patron books are free, and I am going to revise the PDF documents to make it easier for printing booklets like this.
Make sure your PDF version has a blank page after the cover and before the back cover if not you have an early version and the below will not work.
This is a fairly simple process, though stapling can be a pain if you do not have a long reach stapler (check your office).
I have included screen shots from two different printers as my home printer and fancy work printer do this slightly different.
1. Load the paper you intend to use as the cover to feed first. I use thicker tan card stock for the cover and regular copy paper for the rest.
2. Select "Booklet" and Landscaping
or if you have a fancy work printer "Booklet Printing"
3. Make sure if you can't print double sided to pick "front side only"
or if you have a fancy work printer it prints both sides so hit print and your done.
5. Flip the paper over and you are ready to print the other side just pick "back side only", its ok if it shows a blank page this is the empty cover of the interior.
As you can see very easy. If you don't have a long reach stapler you can using two staplers, using one as the base and one as the stapler, I would suggest practicing on some scrap paper first.
Best of luck and enjoy!